“St. Vincent” sticks to the script. You know, the story about the cantankerous grouch who forms an unlikely bond with a younger, usually troubled child with his opposite temperament. A tried and true formula. Despite lacking in originality, however, this classic storyline plays out in enjoyable fashion in “St. Vincent” thanks in large part to its cast, namely — you guessed it — Bill Murray.

Murray’s Vincent character hearkens back to his mainstream heyday, before he gave up traditional comedy. Vincent is a vice-ridden, self-isolating older man who only cares about what’s in his own interest, a classically unlikable main character that Murray has done so effortlessly well in his career. When a recently divorced woman (Melissa McCarthy) moves in next door with her pre-teen son, Oliver (Jaeden Lieberher), Vincent finds himself babysitting the kid one day after school and eventually ropes the woman into paying him to watch him on the regular.

Whereas most of these unlikely relationship films play up the tension between the kid and the mean adult, Oliver is actually more of a quiet kid, and his troubles with school bullies lead Vincent to become his unlikely mentor. The conflict (and humor) comes from the “inappropriate” exposure Oliver gets following Vincent around, and the lessons he gleans that get him into a bit of his own trouble.

Theodore Melfi, making his feature film debut as both writer and director, navigates the clichés and predictability of his own story with subtlety. Although Murray and choices like McCarthy in the “straight role” as the mother and typically dramatic actress Naomi Watts playing a Russian/Eastern European prostitute can take a large chunk of credit for the film’s energy and humor, Melfi endears us to his film by focusing on characters and relationships rather than jokes.

Melfi also uses a really simple storytelling device that pays dividends: he deliberately withholds background information about Vincent, instead dropping little pearls of information as the story goes along. This helps evolve the Vincent character past the shallow hedonism we see at the onset and into a complicated portrait. He relies a bit on the audience judging Vincent and thinking they know exactly what kind of character he is before slowly turning that assumption inside out. It’s a gradual reveal and not pulled off with any trickery whatsoever, which is key given the casual tone of the film, especially because of how it builds to the story’s emotional climax.

Who knows whether the film would even work without Murray, but it’s a blessing to have him putting his most natural talents to work again. Paired with a supporting cast that features a comedic pro in McCarthy and an Oscar nominee in Watts, he has serious talents playing foil to him and that helps immeasurably in keeping his performance (and the whole movie) grounded.

With those elements in play, “St. Vincent” never succumbs to its predictable story and standard- order filmmaking. Instead, it works in a very classic way that doesn’t disappoint. It hits just enough of an emotional note, makes just enough of a connection that it will draw favorably opinions from most everyone.